Semiconductor device

ABSTRACT

A semiconductor device of the present invention includes a resin package, a semiconductor chip sealed in the resin package, and having first and second pads on a front surface, a lead integrated island sealed in the resin package, to one surface of which a back surface of the semiconductor chip is bonded, and the other surface of an opposite side to the one surface of which is partially exposed from a bottom surface of the resin package as a first pad connecting terminal for electrical connection between the first pad and outside and a back connecting terminal for electrical connection between the back surface of the semiconductor chip and outside separately from each other, and a lead formed separately from the lead integrated island, sealed in the resin package, one surface of which is connected with the second pad by a wire, and the other surface of an opposite side to the one surface of which is exposed from a bottom surface of the resin package as a second pad connecting terminal for electrical connection between the second pad and outside, and the semiconductor chip is, on the one surface of the lead integrated island, disposed at a position one-sided to the first pad connecting terminal side, and the first pad and the one surface of the lead integrated island are connected by a wire.

This application is a continuation of application Ser. No. 13/320,528,filed on Dec. 9, 2011. Furthermore, this application claims the benefitof priority of Japanese applications 2009-118833, filed on May 15, 2009.The disclosures of these prior U.S. and Japanese applications areincorporated herein by reference.

TECHNICAL FIELD

As a surface mounted package, a so-called non-lead package for whichextension of leads from a resin package is eliminated, and leads (outerleads) are exposed on a lower surface of the resin package is known.

FIG. 7 is a plan view of a semiconductor device using a non-leadpackage, and transparently shows, by solid lines, members sealed in aresin package.

The semiconductor device 101 using a non-lead package has a structurefor which a semiconductor chip 103 is bonded to a lead frame 102, andthese are sealed by a resin package 104. The resin package 104 is formedin a regular square shape in a plan view.

The lead frame 102 includes an island 105 and four leads 106 separatedfrom the island 105. The island 105 is, in a plan view, formed in aregular square shape whose center overlaps the center of the resinpackage 104 and whose sides are parallel with the sides of the resinpackage 104. The four leads 106 are each disposed so as to be opposed toeach corner portion of the island 105 in a direction along a diagonal ofthe island 105. Each lead 106 is, in a plan view, formed in a regularsquare shape whose sides are parallel with the sides of the resinpackage 104. Lower surfaces of the island 105 and each lead 106 are, asterminals for electrical connection with a substrate on which thesemiconductor device 101 is mounted, exposed on a back surface of theresin package 104.

The semiconductor chip 103 shows a substantially regular square shape ina plan view, and is disposed on the island 105 so that its sides areparallel with the sides of the island 105. A back surface of thesemiconductor chip 103 is bonded to the island 105 via a conductivebonding material. At corner portions of a front surface of thesemiconductor chip 103, pads 107 are formed by exposing a part ofinternal wiring. Between each pad 107 and the lead 106 opposed to thecorner portion of the semiconductor chip 103 at which the pad 107 isformed, a wire 108 is stretched.

CITATION LIST Patent Literature

Patent Document 1: Japanese Published Unexamined Patent Application No.2007-95788

SUMMARY OF INVENTION Technical Problem

For satisfactorily stretching the wire 108 between the lead 106 and thepad 107, it is necessary to have an interval of a fixed interval (forexample, 310 μm) or more therebetween. Accordingly, the lead 106 cannotbe made closer than a fixed distance to the island 105, and the planearea of the resin package 104 (mounting area of the semiconductor device101) is relatively large.

Therefore, considered is a configuration of, as shown in FIG. 8, formingan island 105 rotated by 45° from the state shown in FIG. 7 so that thediagonals of the island 105 become perpendicular to the diagonals of theresin package 104 in a plan view, and disposing at parts opposed to thefour sides of the island 105, respectively, substantiallytriangular-shaped leads 106 two sides of each of which are parallel withtwo sides of the resin package 104.

However, with this configuration, another problem that the accuracy inrecognition of the pad 107 for formation of the wire 108 degradesoccurs. Usually, the position of the pad 107 of the semiconductor chip103 is recognized based on an angle created by a straight line toconnect two alignment marks M provided at an upper left part and a lowerright part of the figure in the front surface of the semiconductor chip103 and a direction parallel to one side of the resin package 104.Therefore, when the island 105 is formed rotated by 45° from the stateshown in FIG. 7, the two alignment marks M are formed separated in adirection parallel to one side of the semiconductor chip 103.Accordingly, the interval between the two alignment marks M cannot besecured large, and the accuracy in recognition of the position of thepad 107 on the semiconductor chip 103 degrades. Consequently, the yieldof wire bonding of the semiconductor chip 103 on the island 105 isreduced.

An object of the present invention is to provide a semiconductor devicewhich allows a reduction in the plane area (mounting area) of a resinpackage, while allowing satisfactory stretching of a wire between thepad and lead.

Solution to Problem

A semiconductor device according to one aspect of the present inventionfor achieving the object described above includes a resin package, asemiconductor chip sealed in the resin package, and having first andsecond pads on a front surface, a lead integrated island sealed in theresin package, to one surface of which a back surface of thesemiconductor chip is bonded, and the other surface of an opposite sideto the one surface of which is partially exposed from a bottom surfaceof the resin package as a first pad connecting terminal capable ofelectrical connection between the first pad and outside and a backconnecting terminal capable of electrical connection between the backsurface of the semiconductor chip and outside separately from eachother, and a lead formed separately from the lead integrated island,sealed in the resin package, one surface of which is connected with thesecond pad by a wire, and the other surface of an opposite side to theone surface of which is exposed from a bottom surface of the resinpackage as a second pad connecting terminal capable of electricalconnection between the second pad and outside, and the semiconductorchip is, on the one surface of the lead integrated island, disposed at aposition one-sided to the first pad connecting terminal side, and thefirst pad and the one surface of the lead integrated island areconnected by a wire.

As a result of the semiconductor chip being disposed at a positionone-sided to the first pad connecting terminal side on the one surfaceof the lead integrated island, an interval where a wire can besatisfactorily stretched (interval where a wire can normally loop) issecured between the first pad on the front surface of the semiconductorchip and a bonding position of a wire on the one surface of the leadintegrated island. Therefore, the wire can be satisfactorily stretchedbetween the bonding position and the first pad. As a result of the firstpad and the one surface of the lead integrated island being connected bythe wire, electrical connection between the first pad and the first padconnecting terminal can be achieved.

Moreover, since the semiconductor chip is disposed at a positionone-sided to the first pad connecting terminal side on the one surfaceof the lead integrated island, even when the lead is disposed close tothe lead integrated island, an interval where a wire can besatisfactorily stretched is secured between the second pad on the frontsurface of the semiconductor chip and the lead. Therefore, the wire canbe satisfactorily stretched between the second pad and the lead. As aresult of the second pad and the lead being connected by the wire,electrical connection between the second pad and the second padconnecting terminal can be achieved.

Accordingly, as a result of the lead being disposed close to the leadintegrated island while electrical connections between the first andsecond pads and the first and second pad connecting terminals can beachieved, the plane area (mounting area) of the resin package can bereduced.

Usually, for fixing the semiconductor chip to the lead integratedisland, a conductive bonding agent paste is interposed between the backsurface of the semiconductor chip and the one surface of the leadintegrated island. Since the conductive bonding agent is a paste, theconductive bonding agent may seep out between the back surface of thesemiconductor chip and the one surface of the lead integrated islandwhen the back surface of the semiconductor chip is bonded to the onesurface of the lead integrated island.

Therefore, it is preferable that, in the one surface of the leadintegrated island, a groove is formed between a bonding position of thesemiconductor chip and a connecting position of the wire.

Accordingly, even when the conductive bonding agent seeps out betweenthe back surface of the semiconductor chip and the one surface of thelead integrated island, the groove can stem the seeping of the bondingagent. Therefore, the conductive bonding agent can be prevented fromreaching the connecting position of the wire on the one surface of thelead integrated island, so that a short circuit due to contact betweenthe conductive bonding agent and the wire can be prevented.

Moreover, it is preferable that the first and second pads are, in thefront surface of the semiconductor chip, disposed at positions one-sidedto an opposite side to the first pad connecting terminal side.

Accordingly, even when the semiconductor chip is disposed at a positionone-sided to the first pad connecting terminal side on the one surfaceof the lead integrated island, the intervals between the first andsecond pads and the lead can be prevented from becoming excessivelylarge. Therefore, wires to be stretched therebetween can be preventedfrom becoming excessively long. Consequently, the wires can besatisfactorily stretched, and an increase in the cost (material cost) ofthe wires can be suppressed.

The semiconductor chip may be disposed so that its part overlaps thefirst pad connecting terminal in a plan view. In other words, thesemiconductor chip may be increased in size to the first pad connectingterminal side to such an extent that a part of the semiconductor chipoverlaps the first pad connecting terminal in a plan view.

Even when the semiconductor chip is increased in size to the first padconnecting terminal side, the interval between the semiconductor chipand the lead is unchanged, so that it is not necessary to keep the leadaway from the lead integrated island. Therefore, a large-sizedsemiconductor chip can be realized without increasing the plane area ofthe resin package, and the wire can be satisfactorily stretched betweenthe second pad and the lead.

The resin package may be formed in a square shape in a plan view. Inaddition, three leads may be provided, and in this case, the first padconnecting terminal may be disposed at one of the corner portions of thebottom surface of the resin package, and the second pad connectingterminals may be disposed one each at the other corner portions of thebottom surface of the resin package.

Moreover, the semiconductor chip may have a protruding part protrudingfrom the lead integrated island in a plan view. In this case, it ispreferable that, on the one surface of the lead closest to theprojecting part, a step for which a part opposed to the projectingportion is one-step lower is formed.

Accordingly, contact of the protruding part with the one surface of thelead can be reliably prevented.

Moreover, when the resin package is formed in a square shape in a planview, it is preferable that the semiconductor chip is formed in a squareshape in a plan view, and disposed so that its side surfaces areparallel with side surfaces of the resin package.

Two alignment marks to recognize the positions of the pads of thesemiconductor chip on the lead integrated island can be formed on adiagonal of the front surface of the semiconductor chip. Therefore, alarge interval can be secured between the two alignment marks, so thatthe positions of the pads of the semiconductor chip can be recognizedwith high accuracy. Consequently, the positions of the pads of thesemiconductor chip on the lead integrated island can be positioned withhigh accuracy.

Moreover, when the semiconductor chip is formed in a square shape in aplan view, it is preferable that, in the lead integrated island, acut-away portion having a straight part to serve as a reference whenpositioning the semiconductor chip with respect to the lead integratedisland is formed by cutting away the lead integrated island from itsside surface.

The semiconductor chip can be easily positioned, with reference to thestraight part formed in the lead integrated island, on the one surfaceof the lead integrated island, in a direction perpendicular to thestraight part.

Further, in the semiconductor device, it is more preferable that twocut-away portions are formed in the lead integrated island, and thestraight parts of the cut-away portions extend in directionsperpendicular to each other.

The semiconductor chip can be easily positioned, with reference to thetwo straight parts extending in directions perpendicular to each other,on the one surface of the lead integrated island, in two directionsperpendicular to the straight parts.

Furthermore, in the semiconductor device, as a result of thesemiconductor chip being disposed on one surface of the lead integratedisland so that an end edge of the semiconductor chip overlaps thestraight part, the semiconductor chip can be further easily positioned.

Moreover, in the semiconductor device, it is preferable that a recessportion that is recessed from the other surface side and opened at itsside surface is formed in the lead, and the resin package enters in therecess portion.

As a result of the resin package entering into the recess portion, thepart of the lead where the recess portion is formed is sandwiched fromboth sides in its thickness direction by the resin package. Thus, thelead can be prevented from dropping out of the resin package.

Moreover, an external form of the resin package may be a hexahedronhaving a regular square shape in a plan view, and in that case, it ispreferable that the lead integrated island includes an island parthaving a side inclined at 45° with respect to any of the sides of theresin package in a plan view.

Moreover, the lead integrated island may have a suspending portionextending from the island part to a side surface of the resin package,and in that case, it is preferable that an end face of the suspendingportion is, on a side surface of the resin package, exposed flush withthe side surface.

Moreover, it is preferable that the lead integrated island includes alead part joined to one side of the island part, and a central portionof the island part and a corner portion of the lead part are formedthicker than a remaining part other than these.

The back connecting terminal may show a square shape having four sidesinclined at 45° with respect to the sides of the resin package.

Moreover, the step is formed lower by 0.03 mm to 0.05 mm than the onesurface of the lead.

A semiconductor device according to another aspect of the presentinvention includes a resin package, a semiconductor chip sealed in theresin package, and having a pad on a front surface, a lead integratedisland sealed in the resin package, to one surface of which a backsurface of the semiconductor chip is bonded, and the other surface of anopposite side to the one surface of which is partially exposed from abottom surface of the resin package as a connecting terminal and a backconnecting terminal capable of electrical connection between the backsurface of the semiconductor chip and outside separately from eachother, and a lead formed separately from the lead integrated island,sealed in the resin package, one surface of which is connected with thepad by a wire, and the other surface of an opposite side to the onesurface of which is exposed from a bottom surface of the resin packageas a pad connecting terminal capable of electrical connection betweenthe pad and outside, and the semiconductor chip is, on the one surfaceof the lead integrated island, disposed at a position one-sided to theconnecting terminal side.

Since the semiconductor chip is disposed at a position one-sided to theconnecting terminal side on the one surface of the lead integratedisland, even when the lead is disposed close to the lead integratedisland, an interval where a wire can be satisfactorily stretched(interval where a wire can normally loop) is secured between the pad onthe front surface of the semiconductor chip and the lead. Therefore, asa result of the lead being disposed close to the lead integrated islandwhile the wire can be satisfactorily stretched between the pad and thelead, the plane area (mounting area) of the resin package can bereduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of a semiconductor device according to anembodiment of the present invention, and transparently shows, by solidlines, members sealed in a resin package, and transparently shows, bybroken lines, parts of a lead frame exposed from a bottom surface of theresin package.

FIG. 2 is a plan view of the semiconductor device shown in FIG. 1, andtransparently shows, by solid lines, parts of a lead frame exposed froma bottom surface of the resin package.

FIG. 3 is a side view of the semiconductor device when viewed from thedirection of arrow A shown in FIG. 1.

FIG. 4 is a side view of the semiconductor device when viewed from thedirection of arrow B shown in FIG. 1.

FIG. 5 is a sectional view taken along the cut line V-V of thesemiconductor device shown in FIG. 1.

FIG. 6 is a sectional view taken along the cut line VI-VI of thesemiconductor device shown in FIG. 1.

FIG. 7 is a plan view of a conventional semiconductor device, andtransparently shows, by solid lines, members sealed in a resin package.

FIG. 8 is a plan view of another conventional semiconductor device, andtransparently shows, by solid lines, members sealed in a resin package.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. FIG. 1 and FIG. 2are plan views of a semiconductor device according to an embodiment ofthe present invention. FIG. 1 transparently shows members sealed in aresin package by solid lines. Also, FIG. 1 transparently shows parts ofa lead frame exposed from a bottom surface of the resin package bybroken lines. FIG. 2 transparently shows only parts of a lead frameexposed from a bottom surface of the resin package by solid lines. FIG.3 is a side view of the semiconductor device when viewed from thedirection of arrow A shown in FIG. 1. FIG. 4 is a side view of thesemiconductor device when viewed from the direction of arrow B shown inFIG. 1. FIG. 5 is a sectional view taken along the cut line V-V of thesemiconductor device shown in FIG. 1. FIG. 6 is a sectional view takenalong the cut line VI-VI of the semiconductor device shown in FIG. 1.

The semiconductor device 1 has a structure for which a semiconductorchip 3 is bonded to a lead frame 2, and these are sealed by a resinpackage 4. The external form of the semiconductor device 1 (resinpackage 4) shows a flat rectangular parallelepiped shape (in the presentembodiment, a hexahedron having a regular square shape in a plan view).

The lead frame 2 is formed by stamping out a thin metal plate (forexample, a thin copper plate), and includes a lead integrated island 5and three leads 6 disposed around the lead integrated island 5.

The lead integrated island 5 has a shape for which a lead part 8 havinga substantially triangular shape in a plan view is joined to one side ofan island part 7 that is in a square shape having four sides inclined at45° with respect to the sides of the resin package 4 in a plan view.

The island part 7 is disposed in a central portion of the resin package4 in a plan view. Suspending portions 9 having square shapes in a planview extend from corner portions of the island part 7 toward sidesurfaces of the resin package 4 to which these corner portions areopposed. An end face of each suspending portion 9 is, on the sidesurface of the resin package 4, exposed flush with this side surface.

The lead part 8 is disposed at one corner portion of the resin package 4in a plan view. The lead part 8 has a side surface that is, on one sidesurface (hereinafter, this side surface is called a “first side surface10”) of the resin package 4, exposed flush with this first side surface10 and a side surface that is parallel at an interval with another sidesurface (hereinafter, this side surface is called a “second side surface11”) of the resin package 4 perpendicular to the first side surface 10.In the lead part 8, by cutting away in a square shape from the sidesurface exposed on the first side surface 10, a first cut-away portion13 having a straight part 12 parallel to the first side surface 10 isformed adjacent to the suspending portion 9 whose end face is exposed onthe first side surface 10. Moreover, in the lead part 8, by cutting awayin a square shape from the side surface parallel to the second sidesurface 11, a second cut-away portion 15 having a straight part 14parallel to the second side surface 11 is formed adjacent to thesuspending portion 9 whose end face is exposed on the second sidesurface 11. Further, a suspending portion 16 having a square shape in aplan view extends from the side surface of the lead part 8 parallel tothe second side surface 11 toward the second side surface 11. An endface of the suspending portion 16 is, on the second side surface 11,exposed flush with the second side surface 11.

In the following, of the four side surfaces of the resin package 4, aside surface that is parallel to the first side surface 10 andperpendicular to the second side surface is called a “third side surface17,” and a side surface that is parallel to the second side surface 11and perpendicular to the first side surface 10 and the third sidesurface 17 is called a “fourth side surface 18.”

In the lead integrated island 5, a central portion of the island part 7and a corner portion of the lead part 8 are formed thicker than aremaining part other than those. In addition, a lower surface of thecentral portion of the island part 7 formed thick shows a square shapehaving four sides inclined at 45° with respect to the sides of the resinpackage 4, and is, on a back surface of the resin package 4, exposed asaback connecting terminal 19. A lower surface of the corner portion ofthe lead part 8 formed thick has, in a plan view, a shape having a side20 extending almost parallel to one side of the lower surface of thecentral portion of the island part 7, sides 21, 22 extending from bothend portions of the side 20 parallel to the first side surface 10 andthe second side surface 11, respectively, aside 23 extending from an endportion of the side 21 parallel to the second side surface 11, and aside 24 extending on the first side surface 10 from which a semicircularshape opened at the side 20 is cut away. The part where the semicircularshape is cut away is formed as a recess portion 26 that is recessed fromthe lower surface of the corner portion of the lead part 8. In therecess portion 26, the resin package 4 enters. The lower surface of thecorner portion of the lead part 8 is, on the back surface of the resinpackage 4, exposed as a pad connecting terminal 27.

The three leads 6 are, in a plan view, disposed at three corner portionsof the four corner portions of the resin package 4 excluding the cornerportion at which the lead part 8 is disposed.

The lead 6 (hereinafter, referred to as a “first lead 6,” except whenthe three leads 6 are collectively referred to) disposed at the cornerportion created by the first side surface 10 and the fourth side surface18 of the resin package 4 shows, in a plan view, a shape having a side28 extending almost parallel to one side of the lower surface of thecentral portion of the island part 7, sides 29, 30 extending from bothend portions of the side 28 parallel to the first side surface 10 andthe fourth side surface 18, respectively, a side 31 extending from anend portion of the side 29 parallel to the fourth side surface 18, aside 32 extending on the first side surface 10, a side 33 extending froma halfway portion of the side 30 in a direction almost parallel to theside 28, and a side 34 extending from an end portion of the side 33parallel to the fourth side surface 18.

A side surface that forms the side 32 of the first lead 6 is, on thefirst side surface 10 of the resin package 4, exposed flush with thefirst side surface 10. Aside surface that forms the side 31 of the firstlead 6 extends parallel at an interval with respect to the fourth sidesurface 18 of the resin package 4. From this side surface toward thefourth side surface 18, a suspending portion 35 having a square shape ina plan view extends. An end face of the suspending portion 35 is, on thefourth side surface 18, exposed flush with the fourth side surface 18.

In the first lead 6, a trapezoidal part 36 surrounded by the sides 30,32 to 34 and a predetermined-width part 37 along the side 28 are formedthinner than a remaining part 38 other than these. An upper surface ofthe trapezoidal part 36 is formed lower by one step (lower by, forexample, 0.03 mm to 0.05 mm) than upper surfaces of the parts 37, 38.Accordingly, the trapezoidal part 36 is formed thinnest in the firstlead 6. The part 38 formed thickest has a side surface 39 that isdisposed on the same straight line as with the side 33, and in a lowersurface of the part 38, a recess portion 40 in a semicircular shapeopened at the side surface 39 is formed. In the recess portion 40, theresin package 4 enters. The lower surface of the part 38 is, on the backsurface of the resin package 4, exposed as a pad connecting terminal 41.

The lead 6 (hereinafter, referred to as a “second lead 6,” except whenthe three leads 6 are collectively referred to) disposed at the cornerportion created by the second side surface 11 and the third side surface17 of the resin package 4 shows, in a plan view, a shape having a side42 extending almost parallel to one side of the lower surface of thecentral portion of the island part 7, sides 43, 44 extending from bothend portions of the side 42 parallel to the second side surface 11 andthe third side surface 17, respectively, a side 45 extending from an endportion of the side 44 parallel to the second side surface 11, and aside 46 extending on the third side surface 17.

A side surface that forms the side 46 of the second lead 6 is, on thethird side surface 17 of the resin package 4, exposed flush with thethird side surface 17. Aside surface that forms the side 45 of thesecond lead 6 extends parallel at an interval with respect to the secondside surface 11 of the resin package 4. From this side surface towardthe second side surface 11, a suspending portion 47 having a squareshape in a plan view extends. An end face of the suspending portion 47is, on the second side surface 11, exposed flush with the second sidesurface 11.

In the second lead 6, a predetermined-width part 48 along the sides 42,43 is formed thinner than a remaining part 49 other than this. The part49 formed relatively thick has a side surface 50 that is disposed on astraight line almost parallel to the side 42, and in a lower surface ofthe part 49, a recess portion 51 in a semicircular shape opened at theside surface 50 is formed. In the recess portion 51, the resin package 4enters. The lower surface of the part 49 is, on the back surface of theresin package 4, exposed as a pad connecting terminal 52.

The lead 6 (hereinafter, referred to as a “third lead 6,” except whenthe three leads 6 are collectively referred to) disposed at the cornerportion created by the third side surface 17 and the fourth side surface18 of the resin package 4 shows, in a plan view, a shape having a side53 almost parallel to one side of the lower surface of the centralportion of the island part 7, sides 54, 55 extending from both endportions of the side 53 parallel to the third side surface 17 and thefourth side surface 18, respectively, a side 56 extending from an endportion of the side 54 parallel to the fourth side surface 18, and aside 57 extending on the third side surface 17.

A side surface that forms the side 57 of the third lead 6 is, on thethird side surface 17 of the resin package 4, exposed flush with thethird side surface 17. Aside surface that forms the side 45 of the thirdlead 6 extends parallel at an interval with respect to the fourth sidesurface 18 of the resin package 4. From this side surface toward thefourth side surface 18, a suspending portion 48 having a square shape ina plan view extends. An end face of the suspending portion 58 is, on thefourth side surface 18, exposed flush with the fourth side surface 18.

In the third lead 6, a predetermined-width part 59 along the sides 53 to55 is formed thinner than a remaining part 60 other than this. The part60 formed relatively thick has a side surface 61 that is disposed on astraight line almost parallel to the side 53, and in a lower surface ofthe part 60, a recess portion 62 in a semicircular shape opened at theside surface 61 is formed. The lower surface of the part 60 is, on theback surface of the resin package 4, exposed as a pad connectingterminal 63.

The large and small thicknesses in the lead integrated island 5 and theleads 6 can be formed by chemical etching or crushing.

The semiconductor chip 3 is, with its front surface (device formingsurface) on which functional elements are formed facing upward, bonded(die-bonded) at its back surface to an upper surface of the leadintegrated island 5 via a conductive bonding agent paste. Thesemiconductor chip 3 is formed in a flat rectangular parallelepipedshape (in the present embodiment, a hexahedron having a regular squareshape in a plan view), and is, in a plan view, with its twoperpendicular sides being along the straight part 12 of the firstcut-away portion 13 and the straight part 14 of the second cut-awayportion 15, disposed at a position one-sided to the pad connectingterminal 27 side in the upper surface of the lead integrated island 5.The semiconductor chip 3 protrudes from the lead integrated island 5 atits two corner portions 64A, 64B closest to the second lead 6 and thethird lead 6, respectively.

On the front surface of the semiconductor chip 3, four first to fourthpads 65 to 68 are formed at positions one-sided to the third lead 6 sideby exposing a part of a wiring layer from a surface protective film. Inthe present embodiment, the first pad 65 is disposed at the cornerportion on the front surface of the semiconductor chip 3 closest to thethird lead 6. The second pad 66 is disposed at a position with aninterval kept in a direction that is parallel with the fourth sidesurface 18 with respect to the first pad 65. The third pad 67 isdisposed at a position with an interval kept in a direction that isparallel with the third side surface 17 with respect to the first pad65. The fourth pad 68 is disposed between the first pad 65 and thesecond pad 66 with intervals kept with these.

Between the first pad 65 and an upper surface of the suspending portion9 of the lead integrated island 5 that is disposed between the secondlead 6 and the third lead 6, a wire 69 made of a thin gold wire isstretched. Accordingly, the first pad 65 is electrically connected withthe lead integrated island 5, and is electrically connected with the padconnecting terminal 27 formed by its lower surface.

Between the second pad 66 and the upper surface of the part 38 of thefirst lead 6, a wire 70 made of a thin gold wire is stretched.Accordingly, the second pad 66 is electrically connected with the firstlead 6, and is electrically connected with the pad connecting terminal41 formed by its lower surface.

Between the third pad 67 and an upper surface of the part 49 of thesecond lead 6, a wire 71 made of a thin gold wire is stretched.Accordingly, the third pad 67 is electrically connected with the secondlead 6, and is electrically connected with the pad connecting terminal52 formed by its lower surface.

Between the fourth pad 68 and an upper surface of the part 60 of thethird lead 6, a wire 72 made of a thin gold wire is stretched.Accordingly, the fourth pad 68 is electrically connected with the thirdlead 6, and is electrically connected with the pad connecting terminal63 formed by its lower surface.

In the present embodiment, as shown in FIG. 1, the three leads 6 are, ina plan view, disposed at the three corner portions of the four cornerportions of the resin package 4 excluding the corner portion at whichthe lead part 8 is disposed. In addition, from the first to fourth pads65 to 68 of the semiconductor chip 3 disposed one-sided to the remainingcorner portion of the resin package 4, the wires 69 to 72 extend to thethree leads 6 and the suspending portion 9 between the second and thirdleads 6. Accordingly, in the resin package 4, when the resin package 4is divided into two isosceles triangles by a diagonal extending in anopposing direction between the first lead 6 and the second lead 6,bonding is applied in a one-sided manner to the side where the thirdlead 6 is disposed (opposite side to the side where the lead part 8 isdisposed).

On an upper surface of the island part 7 of the lead integrated island5, a linear groove 73 extending parallel to the first side surface 10 ofthe resin package 4 is formed between the bonding position of thesemiconductor chip 3 and the connecting position of the wire 69.

As in the above, the back connecting terminal 19 and the pad connectingterminals 27, 41, 52, 63 are exposed on the back surface of the resinpackage 4. Therefore, the semiconductor device 1 can be surface-mountedon a wiring board.

As a result of the semiconductor chip 3 being disposed at a positionone-sided to the pad connecting terminal 27 side in the upper surface ofthe lead integrated island 5, an interval where the wire 69 can besatisfactorily stretched (interval where a wire can normally loop) issecured between the first pad 65 on the front surface of thesemiconductor chip 3 and the upper surface of the suspending portion 9of the lead integrated island 5. Therefore, the wire 69 can besatisfactorily stretched between the first pad 65 and the suspendingportion 9. As a result of the first pad 65 and the upper surface of thelead integrated island 5 being connected by the wire 69, electricalconnection between the first pad 65 and the pad connecting terminal 27can be achieved.

Moreover, since the semiconductor chip 3 is disposed at a positionone-sided to the pad connecting terminal 27 side on one surface of thelead integrated island 5, even when the leads 6 are disposed close tothe lead integrated island 5, intervals where the wires 70 to 72 can besatisfactorily stretched are secured between the second to fourth pads66 to 68 on the front surface of the semiconductor chip and the leads 6,respectively. Therefore, the wires 70 to 72 can be satisfactorilystretched between the second to fourth pads 66 to 68 and the leads 6,respectively. As a result of the second to fourth pads 66 to 68 and theleads 6 being connected by the wires 70 to 72, respectively, electricalconnection between the second to fourth pads 66 to 68 and the padconnecting terminals 41, 52, 63 of the lower surfaces of the leads 6 canbe achieved.

Accordingly, as a result of the leads 6 being disposed close to the leadintegrated island 5 while electrical connection between the first tofourth pads 65 to 68 and the pad connecting terminals 27, 41, 52, 63 canbe achieved, the plane area (mounting area) of the resin package 4 canbe reduced.

Moreover, since the groove 73 is formed, in the upper surface of thelead integrated island 5, between the bonding position of thesemiconductor chip 3 and the connecting position of the wire 69, evenwhen the conductive bonding agent seeps out between the back surface ofthe semiconductor chip 3 and the upper surface of the lead integratedisland 5, the groove 73 can stem the seeping of the bonding agent.Therefore, the conductive bonding agent can be prevented from reachingthe connecting position of the wire 69 of the upper surface of the leadintegrated island 5, so that a short circuit due to contact between theconductive bonding agent and the wire 69 can be prevented.

Moreover, the first to fourth pads 65 to 68 are disposed, in the frontsurface of the semiconductor chip 3, at positions one-sided to anopposite side to the pad connecting terminal 27 side, that is, the padconnecting terminal 63 side. Accordingly, even when the semiconductorchip 3 is disposed at a position one-sided to the pad connectingterminal 27 side in the upper surface of the lead integrated island 5,the intervals between the second to fourth pads 66 to 68 and the leads 6can be prevented from becoming excessively large. Therefore, the wires70 to 72 to be stretched therebetween can be prevented from becomingexcessively long. Consequently, the wires 70 to 72 can be satisfactorilystretched, and an increase in the cost (material cost) of the wires 70to 72 can be suppressed.

As shown in FIG. 1, the semiconductor chip 3 is disposed so that itspart overlaps the pad connecting terminal 27 in a plan view.Accordingly, the semiconductor chip 3 can be increased in size to thepad connecting terminal 27 side. Even when the semiconductor chip 3 isincreased in size to the pad connecting terminal 27 side, the intervalsbetween the semiconductor chip 3 and the leads 6 are unchanged, so thatit is not necessary to keep the leads 6 away from the lead integratedisland 5. Therefore, a large-sized semiconductor chip 3 can be realizedwithout increasing the plane area of the resin package 4, and the wires70 to 72 can be satisfactorily stretched between the second to fourthpads 66 to 68 and the leads 6, respectively.

Moreover, the semiconductor chip 3 has the parts 64A, 64B protrudingfrom the lead integrated island 5 in a plan view. In the first lead 6,the upper surface of the trapezoidal part 36 opposed to the protrudingpart 64A is formed lower by one step than the upper surfaces of theother parts 37, 38. Accordingly, contact of the protruding part 64A withthe upper surface of the first lead 6 can be reliably prevented.

Also, in the second lead 6, the upper surface of apart opposed to thepart 64B protruding from the lead integrated island 5 of thesemiconductor chip 3 may be formed lower than the upper surfaces of theother parts. In this case, contact of the protruding part 64B with theupper surface of the second lead 6 can be reliably prevented.

Moreover, the semiconductor chip 3 is formed in a square shape in a planview, and is disposed so that its side surfaces are parallel with theside surfaces of the resin package 4. Accordingly, two alignment marks(not shown) to recognize the positions of the three pads 65 to 68 of thesemiconductor chip 3 on the lead integrated island 5 can be formed on adiagonal of the front surface of the semiconductor chip 3. Therefore, alarge interval can be secured between the two alignment marks, so thatthe positions of the pads 65 to 68 of the semiconductor chip 3 can berecognized with high accuracy. Consequently, the positions of the pads65 to 68 on the lead integrated island 5 can be positioned with highaccuracy.

Moreover, in the lead integrated island 5, the cut-away portion 13having the straight part 12 and the cut-away portion 15 having thestraight part 14 extending in a direction perpendicular to the straightpart 12 are formed. Therefore, as a result of the semiconductor chip 3being disposed on the upper surface of the lead integrated island 5 withreference to the two straight parts 12, 14 so that end edges of thesemiconductor chip 3 overlap the straight parts 12, 14, thesemiconductor chip 3 can be easily positioned, on the lead integratedisland 5, in two directions perpendicular to the straight parts 12, 14.

Moreover, the recess portions 40, 51, 62 are formed in the three leads6, respectively, and the resin package 4 enters in these recess portions40, 51, 62. Therefore, the parts of the leads 6 where the recessportions 40, 51, 62 are formed are sandwiched from both sides in itsthickness direction by the resin package 4. Thus, the leads 6 can beprevented from dropping out of the resin package 4.

In the above, a description has been given of an embodiment of thepresent invention, but the present invention can also be carried out inother modes.

For example, the wire 69 may not necessarily be stretched between thefirst pad 65 and the lead integrated island 5. In this case, sinceelectrical connection between the first pad 65 and the pad connectingterminal 27 is not achieved, the pad connecting terminal 27 serves as adummy terminal not contributing to electrical connection with the firstpad 65.

The shape of the recess portions 40, 51, 62 is not limited to asemicircular shape in a plan view, and may be, for example, an Npolygonal shape in a plan view (N≧3).

Although the embodiments of the present invention have been described indetail, these are merely specific examples used to clarify the technicalcontents of the present invention, and the present invention should notbe interpreted as being limited to only these specific examples, and thespirit and scope of the present invention shall be limited only by theaccompanying claims.

Moreover, the components mentioned in the embodiments of the presentinvention can be combined in the scope of the present invention.

The present application corresponds to Japanese Patent Application No.2009-118833 filed on May 15, 2009 in the Japan Patent Office, and theentire disclosure of this application is herein incorporated byreference.

REFERENCE SIGNS LIST

1: Semiconductor device, 3: Semiconductor chip, 4: Resin package, 5:Lead integrated island, 6: Lead, 12: Straight part, 13: Cut-awayportion, 14: Straight part, 15: Cut-away portion, 19: Back connectingterminal, 26: Recess portion, 27: Pad connecting terminal (first padconnecting terminal), 36: Trapezoidal part, 40: Recess portion, 41: Padconnecting terminal (second pad connecting terminal), 51: Recessportion, 52: Pad connecting terminal (second pad connecting terminal),62: Recess portion, 63: Pad connecting terminal (second pad connectingterminal), 64A: Corner portion (protruding part), 64B: Corner portion(protruding part), 65: First pad (first pad), 66: Second pad (secondpad), 67: Third pad (second pad), 68: Fourth pad (second pad), 69: Wire,70: Wire, 71: Wire, 72: Wire, 73: Groove

What is claimed is:
 1. A semiconductor device comprising: a resinpackage; a semiconductor chip sealed in the resin package, and havingfirst and second pads on a front surface; a lead integrated islandsealed in the resin package, to one surface of which a back surface ofthe semiconductor chip is bonded, and the other surface of an oppositeside to the one surface of which is partially exposed from a bottomsurface of the resin package as a first pad connecting terminal; and alead formed separately from the lead integrated island, sealed in theresin package, one surface of which is connected with the second padelectrically, and the other surface of an opposite side to the onesurface of which is exposed from a bottom surface of the resin packageas a second pad connecting terminal capable of electrical connectionbetween the second pad and outside, wherein a center of mass of thesemiconductor chip is away from a center of the resin package.
 2. Thesemiconductor device according to claim 1, further comprising aconnecting member electrically connecting the lead with the second pad.3. The semiconductor device according to claim 2, wherein the connectingmember includes wire.
 4. The semiconductor device according to claim 1,wherein in the one surface of the lead integrated island, a groove isformed.
 5. The semiconductor device according to claim 4, wherein thefirst and second pads are, in the front surface of the semiconductorchip, disposed at positions one-sided to an opposite side to the firstpad connecting terminal side.
 6. The semiconductor device according toclaim 1, wherein the first and second pads are, in the front surface ofthe semiconductor chip, disposed at positions one-sided to an oppositeside to the first pad connecting terminal side.
 7. The semiconductordevice according to claim 1, wherein the semiconductor chip is disposedso that its part overlaps the first pad connecting terminal in a planview.
 8. The semiconductor device according to claim 1, wherein theresin package is formed in a square shape in a plan view, three leadsare provided, the first pad connecting terminal is disposed at one ofthe corner portions of the bottom surface of the resin package, and thesecond pad connecting terminals are disposed one each at the othercorner portions of the bottom surface of the resin package.
 9. Thesemiconductor device according to claim 8, wherein the semiconductorchip has a protruding part protruding from the lead integrated island ina plan view, and on the one surface of the lead closest to theprojecting part, a step for which apart opposed to the projectingportion is one-step lower is formed.
 10. The semiconductor deviceaccording to claim 9, wherein the step is formed lower by 0.03 mm to0.05 mm than the one surface of the lead.
 11. The semiconductor deviceaccording to claim 1, wherein the resin package is formed in a squareshape in a plan view, and the semiconductor chip is formed in a squareshape in a plan view, and disposed so that its side surfaces areparallel with side surfaces of the resin package.
 12. The semiconductordevice according to claim 1, wherein the semiconductor chip is formed ina square shape in a plan view, and in the lead integrated island, acut-away portion having a straight part to serve as a reference whenpositioning the semiconductor chip with respect to the lead integratedisland is formed by cutting away the lead integrated island from itsside surface.
 13. The semiconductor device according to claim 12,wherein two cut-away portions are formed in the lead integrated island,and the straight parts of the cut-away portions extend in directionsperpendicular to each other.
 14. The semiconductor device according toclaim 12, wherein the semiconductor chip is disposed so that its endedge overlaps the straight part.
 15. The semiconductor device accordingto claim 1, wherein a recess portion that is recessed from the othersurface side and opened at its side surface is formed in the lead, andthe resin package enters in the recess portion.
 16. The semiconductordevice according to claim 1, wherein an external form of the resinpackage is a hexahedron having a regular square shape in a plan view.17. The semiconductor device according to claim 16, wherein the leadintegrated island includes an island part having a side inclined at45.degree. with respect to any of the sides of the resin package in aplan view.
 18. The semiconductor device according to claim 17, whereinthe lead integrated island has a suspending portion extending from theisland part to a side surface of the resin package.
 19. Thesemiconductor device according to claim 18, wherein an end face of thesuspending portion is, on a side surface of the resin package, exposedflush with the side surface.
 20. The semiconductor device according toclaim 17, wherein the lead integrated island includes a lead part joinedto one side of the island part, and a central portion of the island partand a corner portion of the lead part are formed thicker than aremaining part other than these.
 21. The semiconductor device accordingto claim 1, further comprising a back connecting terminal capable ofelectrical connection between the back surface of the semiconductor chipand outside, the back connecting terminal exposed from the bottomsurface of the resin package in separately from the first pad connectingterminal.
 22. The semiconductor device according to claim 21, whereinthe back connecting terminal shows a square shape having four sidesinclined at 45.degree. with respect to the sides of the resin package.23. The semiconductor device according to claim 1, wherein thesemiconductor chip is, on the one surface of the lead integrated island,disposed at a position one-sided to the first pad connecting terminalside.
 24. The semiconductor device according to claim 1, wherein thefirst pad and the one surface of the lead integrated island areconnected by a wire.
 25. A semiconductor device comprising: a resinpackage; a semiconductor chip sealed in the resin package, and having apad on a front surface; a lead integrated island sealed in the resinpackage, to one surface of which a back surface of the semiconductorchip is bonded, and the other surface of an opposite side to the onesurface of which is partially exposed from a bottom surface of the resinpackage as a connecting terminal; and a lead formed separately from thelead integrated island, sealed in the resin package, one surface ofwhich is connected with the pad electrically, and the other surface ofan opposite side to the one surface of which is exposed from a bottomsurface of the resin package as a pad connecting terminal, wherein acenter of mass of the semiconductor chip is away from a center of theresin package.